Good work with your experiment! I've had an ex-anorexic girlfriend, and my actual fiancée suffers from secondary vaginismus, so I can relate to many of the problems and delights that Billy experiences. If you want to take in consideration further ways of self-modification, you could try hormone therapies. If I understand them correctly, topic estrogen therapy could be an improvement for the vaginismus condition, while testosterone therapy could increase your sex drive and the general harmony in the couple (contrary to popular belief, a testosterone increase does not promote aggressivity). Caution however, since t-therapy is considered mildly experimental.